"The search warrant authorized investigators to look for medical records relating to Michael Jackson and all of his reported aliases," the statement said. "Dr. Murray was present during the search of his home and assisted the officers."

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Investigators left Murray's home about noon, he said, taking cell phones and a computer hard drive. "As of 2 p.m., the search at Dr. Murray's office continues," the statement said.

Murray, a Texas-based cardiologist, allegedly gave Jackson the anesthetic propofol -- commonly known by the brand name Diprivan -- in the 24 hours before he died, said the source, who asked not to be named because the individual was not authorized to speak to the news media. Watch a profile of Murray »

In a statement Monday, the doctor's attorneys said they wouldn't comment on "rumors, innuendo or unnamed sources." In the past, they have said Murray never prescribed or administered anything that could have killed Jackson. Watch CNN's Ted Rowlands report on drug allegation »

Last week, Texas authorities searched Murray's Houston medical office and storage unit, looking for "evidence of the offense of manslaughter," according to court documents.

Among the items removed from Murray's office were a computer; 27 tablets of phentermine, a prescription-strength appetite suppressant; 1 tablet of clonazepam, an anti-anxiety medication; and some Rolodex cards.

From Murray's storage unit, authorities removed two computer hard drives; an "important contact list"; a suspension notice from Houston's Doctor Hospital; notices from the Internal Revenue Service; and a laundry list of medical and hospital documents.

Chernoff, a Houston lawyer hired by Murray soon after Jackson's death, confirmed at the time that Los Angeles police detectives and federal DEA agents used a search warrant to enter Murray's office in northeast Houston on Wednesday morning.

Chernoff said members of Murray's legal team were at the medical office during the search, which he said "was conducted by members of the DEA, two robbery-homicide detectives from the Los Angeles Police Department and Houston Police officers."

Police have interviewed Murray twice since Jackson's death. A third interview was scheduled for July 24, but was postponed after the search warrants were executed. It's unknown when the next interview will take place.

Among those who have indicated that Jackson may have been using dangerous prescription medication are nutritionist Cherilyn Lee, who said Jackson pleaded for the powerful sedative Diprivan despite being told of its harmful effects.

Meanwhile, the Los Angeles County coroner's office continues to investigate the cause of Jackson's death on June 25. It has been waiting on toxicology lab results, but a final autopsy report is expected as soon as this week, a coroner's spokesman has said.